Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries full disclosure burden, and it delivers: deterministic one-shot retrieval, draining of only the pinned rendezvous relay, deletion/NACK of wrong DMs, acceptance/ACK of the first match, courier_not_found on no match, and client reinitialization without restart. This is unusually complete behavioral context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is longer than average but dense and well-structured, with the key warning front-loaded. Each sentence contributes behavioral or routing detail; a small amount of protocol terminology (ACK/NACK, scan stops) could be trimmed without losing value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return values are covered externally. The description covers prerequisites, the main relay path, the alternative card path, failure behavior, side effects, and explicit anti-polling guidance, making it complete for a complex 4-parameter tool with no annotations.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline is 3, but the description adds meaningful semantics beyond the schema: it defines the retrieval tuple (sender_npub, service, dpop_token), explains that dpop_token is not needed on the credential_card path, and clarifies that service must match the one used in request_credential_channel.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb and resource: 'Pick up credentials from the Secure Courier.' It clearly states the tool completes the CREDENTIAL-DELIVERY flow and distinguishes itself from its ownership-proof counterpart, receive_npub_proof, so an agent can tell it apart from siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit call conditions are given: only call after the user confirms they have replied, and do NOT poll, loop, or retry. It also explains the alternative credential_card path that bypasses relay access, giving clear situational routing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.